We are studying the characteristics of drug induced euphoria and experimenting with the modification of this effect in man. We are measuring the physiological effects, metabolism and kinetics, of cocaine in human volunteers. The investigation is directed to determining the neurochemical basis of the psychological effects which follow the ingestion of euphoriants. Using cocaine, lidocaine, amphetamine, and placebo, we are comparing the differences in physiological and psychological effects attained with varying forms, dosages, and routes of administration. To get a clearer picture of the euphoriant action of these drugs we are attempting to expand and refine our methods of psychological testing. We are experimenting with the block of drug induced euphoria using lithium and naloxone and are considering using other blockers, such as AMPT and propranolol, to test their blocking effect. We are investigating a new form of cocaine abuse, cocaine paste smoking. We will obtain biological specimens and psychological measures from native Peruvian volunteers; specimens and data will be analyzed in our laboratories at Yale.